Surfactin Ameliorated the Internalization and Inhibitory Performances of Bleomycin Family Compounds in Tumor Cells.

The cationic glycopeptide bleomycin (BLM) is a broad-spectrum chemotherapy drug clinically applied to treat various malignant tumors. The poor cell membrane permeability of BLM, which is prone to high dose usage and may consequently induce dose-dependent lung toxicity, is a sticking point to limit clinical applications of BLM. As a commercial biosurfactant, the anionic lipopeptide surfactin (SF) is well known for its potent ability to disturb membranes and widely applied in cosmetic area as a permeabilization synergist. In this work, our investigations showed that SF could ameliorate the cell internalization of BLM, and the combined usage of SF notably improved the antitumor activity of BLM or its analogues while having no obvious effects on normal cells. Subsequent assessments on the subcutaneous treatment of A375 melanoma in mice demonstrated that SF could also enhance the therapeutic effects of BLM family compounds in subeffective doses, with no obvious toxicities on lungs and skin. Also, our preliminary results suggested the formation of complex micelles at the nanoscale by the self-assembly of BLM and SF, which may contribute to the ameliorated internalization and the antitumor effect of BLM. Therefore, SF could be applied as a potential synergist for BLM to reduce its treatment dose while maintaining the therapeutic effect on treatment of skin carcinoma, which provides us an alternative way to minimize the side effects of clinical BLM and facilitate the development of new BLM-type drugs.